Piston



Patented Aug.- 3, 1948 a UNITED STATES PATENT oFEicE PSTON Philip S. Webster, North Muskegon, Mich.4

f AppllcatlonMarch 21, 1946, Serlal No. 655,944

This invention relates to improvements in pistons for internal combustion engines and more particularly to liquid cooled pistons of the ilexible dome type.

Flexible dome pistons are particularly advantageous in that they prevent excessive pressure lin the combustion chamber during the combustion cycle. Liquid cooled pistons are advantageous in that they prevent the formation of localized hot spots. Both of these characteristics tend to prevent detonation and permit the use of lower grade fuel.

It is therefore an object of this invention to provide a piston which tends to prevent detonation.

Another object of this invention is to provide a. flexible dome piston, the dome of which is liquid cooled.

A further object of the invention is to provide a piston in which the dome'is flexible, liquid cooled and the lateral thrust faces of the piston are lubricated by the cooling medium.

A still further object of the invention is to provide a piston which will have minimum wear in the upper portion and maintain the'proper piston ring alignment at all times.

'I'hese objects are obtained by providing the piston with a dome which has a sliding iit over the head of the piston trunk and is constantly urged to extended position by a spring of sufiicient force to resist exing of the dome toward the head except during the combustion cycle. The space between the dome and the head, when in the extended position of the dome, is supplied with lubricant under pressure. Inlet feed lines ex-v tending from the piston pin to this space are pro-l vided with checkvalves, and outlet feed lines from this space extend to the lateral thrust sides of the piston trunk where they are closed or opened by the movement of the dome. Lubricant under pressure is supplied tothe piston pin in the customary manner. When the dome is extended,

as during all butthe combustion cycle, the space y below it and' between it and the head is lled with liquid lubricantV which is fedthrough the inlet lines. During the combustion cycle, the dome is compressed against the head, and the liquid lubricant `in said space is forced outl through the outlet feed lines to the lateral thrust sides of the piston trunk, the check valves preventing movement of the lubricant from said space to the inlet lines. A reservoir for a predetermined amount of such lubricant is provided in such sides so that the lateral thrust faces of the piston arealways supplied with lubricant. The excess amount of s claim. (Cl. 12s-'176) lubricant in such reservoir is drained to the crank case through the interior of the trunk. The dome is retained on the head of the trunk by a locking ring which also provides a bearing for absorbing the upper component of the lateral thrust force acting on the piston. `Thus the piston fiexes to prevent excessive pressure in the combustionV chamber during the combustion cycle, while such flexing aids in cooling the dome of the piston and maintenance ofv an evenly distributed moderate temperature as well as positive lubrication of the lateral thrust faces of the piston. Its useful life is lengthened by the prevention of undue wear on the upper portion by the action of the dome locking ring.

The novel features, which are considered characteristic of the invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specic embodiment when read in connection with the accompanying drawing, in which:

.Figure 1 vis a cross-sectional view of a piston embodying the invention taken on the axis of the piston pin;

Figure 2 is a sectional view taken on the line 2-2 of Figure 1, but with the piston pin and connecting rodv removed for the sake of clarity in @+4 of Figure 1.

Referring more particularly to the drawings, the piston comprises a trunk I0 having a head Il and a skirt i3.` The head is connected to the body by a neck It. The diameter of the head i I is less than the diameter of the skirt i3 and the y diameter of the neck I is less than the diameter of the head il. The neck M lforms a circular recess extending around the trunk I0. The trunk lil is provided with the customary pin bosses' l5.

' 3 oil line Il drilled llongitudinally thereof which is belt formed in the outer surfaces of its depending skirt in which standard piston rings (not shown) are carried. Before the dome is inserted over the head li, there is positioned on the head a circular-shaped bellows type spring which is located on the head Il by a centering pin 26. This bellows type'of spring is made of spring steel and has suilicient tension to maintain the dome in the extended position shown in Figure l during all but the combustion cycle. In the combustion cycle the force of combustion compresses the spring 25 and moves the dome 2l to the compressed position shown in Figure 2.

In order to keep the dome 2l on the head il there is provided a locking ring 21 made in two parts and preferably vformed of east iron or steel. The locking ring 2l has an upper internally pro- Jecting flange 28 which fits in a groove formed at the lower end of the skirt of the dome 2l. It also has a lower inwardly projectingV flange 2! which extends inwardly of and abuts against the bottom of the head Il to keep the dome I4 from moving outwardly with respect to the head. Each half of the locking ring is provided with similarly shaped dogs 33 which interlock with each other, asshown in Figure 3, when the two halves o! the ring are forcibly snapped together. The ring 21 is assembled when the piston is compressed a sumcient amount to permit the ilange 2l to enter below the bottom of head Il. The ring 21 also acts as a bearing and guide for the dome and prevents the dome from rubbing against the cylinder walls. As it is spaced above the skirt Il and the center line Aof the pin II, it absorbs the .upper component of the lateral thrust for acting on the piston and takes the wear which would otherwise be imparted to the upper portion of the piston. To disengage the dome 2l from the head. itis only necessary to spring the dogs 33 of one section of the locking ring suiiiciently to disengage them from the dogs 31 of the other section, whereupon both sections o! the ring may be removed laterally oi the dome and trunk. The length of the skirt of the dome is proportioned to the thickness of the head il so that when the spring 25 is fully compressed the flange 2l will be spaced from the top of the skirt Il. Space is provided between the neck I4 and the inner edge oi the flange 2! for the purpose of permitting 'the passage of oil therebetween.

In order to keep the temperature of the dome 24 evenly distributed and moderate during the operation of the piston, provision is made for the passing of fresh cooling oil through the space between the head il and the top of the dome 24. The continuous circulation of lubricating oil through this space absorbs heat from the top of the dome and disburses it nearly uniformly throughout the piston, thus preventing the formation of localized hot spots on the dome which tend to cause -knocking and detonation. To accomplish this in connection with the flexing of the dome during the combustion cycle, the piston trunk is provided with oil lines` Il extending from 4 the grooves 2l upwardly to the top of the head i I. At their upper ends. each line is providedwith a conventional bail check designated generally at Il. Through these lines the oil under pressure in the pin It is also supplied to the space above :the head Il during all but the combustion cycle.

Exhaust oil lines 3| extend radially outward, as shown in Figure 2, from the top oi' the head i I to the bottom of the head ii at the lateral thrust sides of the piston. When the head il is extended' as shown in Figure l, the lower end of the lines Il is closed by the flange 29, thusretaining the oil in the space below the dome. However, when the dome is compressed toward the head Il during the combustion cycle, the lower ends ot the oil lines Ii are opened and the oil in the space between -the dome and the head is forced outwardly through the lines 3| into the recess formed at the neck il. The oil carried in this recess is continuously in contact with the cylinder wall opposite the lateral thrust faces Vof the trunk. Ithus lubricating that wall and the lateral thrust faces of the piston. However, in order to prevent an excess supply ci oil in this recess, and in order to prevent the creation of back pressure. oil holes l2 extend from the surface of the neck il into ;the interior of the trunk. Oil passing through these holes drains to the crank case of the engine.

the dome is alternately compressed and extended with reference to the head Il, the movement o1' the dome toward and away from the head I l in connection with the check valve Il acts as af, pump aiding in pumping the oil out of the space under the dome. This aids the pressure system in accomplishing the continuous circulation of cooling oil and eliminates the need of an auxiliary qu dump. Although only one embodiment of the invention is shown and described herein, it will `be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention or scope of the following claims.

' Iclaim:

. 1, A piston comprising a trunk provided 4with a. head. a recess extending around said trunk below said head to form a lower surface on said lhead, a dome having a skirt portion slidably .j'vent oil from being forced into said passage from 60 the space between said dome and said head. and an oil passage extending from the top of said head to said lower surface at a point adapted .to be closed by said iiange in the extendedposition of said dome.

2. A piston having a trunk provided with pislton pin bosses. a hollow piston pin mounted in said bosses, an oil passage extending from the interior of one of said bosses to the top of said trunk. a. check valve in said passage positioned to open upwardly to permit liquid to pass from said boss and to said top end of said passageway, means for conveying oil from the interior of said pin to said passageway. a dome ilexihly carried by said trunk and movable to extended position to provide a space below the top of said dome and above the top or said trunk into which a cooling lubricant may be delivered from said passage-way, and an outlet from said space noi-,

m'ally closed when said dome is in fully extended position.

3. A piston comprising a bearings for a pistonpin, a recess in the exterior wallo! said trunk, a dome movably mounted on said trunk. a groove in the outer surface of saidv bearings for a'piston pin, a recess in the exterior wall of said trunk, a dome movably mounted'on ,said trunk.'a groove inthe outer surface of 'said dome, and a locking ring having an upper internal flange tting into said groove and a lower internal flange extending into said recess, said ring having an outer bearing surface spaced i above said bearings whereby said ring limits the outward flexing of said dome and 'provides a bearing for the upper component oflateral thrust on said piston and at the same time maintains the domeportion concentric with the cylinder trunk provided with.

5,. A piston having a trunk provided with piston pin bosses, a hollow piston pin mounted .in said bosses, an oilpassage extending from the interior of one of said bosses to the top of said trunk. a check valve in said passage positioned to open upwardly topermit oil to pass from said boss to thetop of said trunk, means for conveying oil from the interior of said hollow pin to said passage. a dome carried'by said trunk and movable from contracted to extended position to pro- Vvide a space below the top of said dome and above the top of said trunk into which loil may be delivered from sadpassage, and a discharge passage for directing oil from said space,

PHILIP s. WEBSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS,

Number Name Date 1,825,163 Schweter Sept.. 29. i931 1,856,107 Mellor May 3, 1932 2,407.429 Kuttner Sept. 10, 1946 y FOREIGN PATENTS Number Country Date 38,607 Netherlands i936 

